Variable ratio planetary transmission



,mach 22, 1949, w. F. BERCK VARIABLE RATIO PLANETRY TRANSMISSION Filed Aug. 8, 1945 A JNVENTOR.

67 WML/AM F. BERCK Patented Mar. 22, 1949 UNI'ED STATES PATENT OFFICE VARIABLE RATIO PILANETABY TRAN SMI S SION Application August 8,

Claims.

rihis invention relates generally to transmission mechanisms, and is more particularly directed to transmission mechanisms of thek planetary gear type.

It is the principal object of,l the present invention to provide an improved efficient planetary geary transmission mechanism whose ratio of transmission can be selectively varied by eX- ceedingly small increments, and which is capable oi positive drive transmission between the driving and driven elements with a comparatively low overall torque.

One form which the invention may assume is exempliiied in the following description and illustrated by way of example in the accompanying drawings, in which:

Fig. l. is a plan View of the transmission unit embodying the features of the. present invention with the cover of the casing removed and with the upper and lower planet carriers also removed in order to show certain features of construction.

53 is a fragmentary view in longitudinal section through the transmission housing, disclosing the transmission gears in full.

Fig. 3 is a plan View of the lower planet carrier, showing the mounting of the gears thereon.

4 is a sectional View through the lower planet carrier taken on line 4-4 of Fig. 3.

Fig. 5 is a sectional View through the upper planet carrier taken on line 5,--5 of Fig. I8.

Fig. 6 is a cross-sectional View through the upper and lower planet carriers, the lower half thereof being taken along the line G- of Fig; 3 and the upper half along the line (ia-Gaf of Fig. 7.

Fig. 'l rer.

Although the transmission mechanism disclosed on the draw-ings is useful for many pur-A is a plan View of the upper planet carposes, it is particularly designed for use in ob,-

taining changes in transmission ratios between the driving and driven elements in relatively small fractional amounts. More specifically, the transmission has unusual value as a Calibrating device between the measuring mechanism and the counting or indicating mechanism of a meter.

The embodiment illustrated in the drawings includes a casing lll enclosing the transmission mechanism, and comprising opposed spaced s-ubstantially parallel top and bottom walls Il, l2, with the latter provided with a bearing web i3 intermediate the end walls Ill, l5. Adrive shaft E6, suitably secured to a longitudinally extend ing hub l'l of a driving pinion i8. journaled Within the bottom casing wall IZ, has its forward 1945, Serial N0'. 609,544

(Cl. 'i4-6,81)

extension t9' projecting across the transmission casing for rotatable reception within the driven shaft of the'.l transmission, which isA journaled in the: top wall, l=| of the casing. A. ,driven sun gearl 2l attached tov the driven, shaft 2Q and meshesV with; planet'`r pinions. 22 secured: to shafts 23 rotatably mounted in ai planetl gear carrier 26 securedi to; the drive shaft. extension i9. The attire-mentioned: planet pinions: are each` secured to. a shaft `23 on one side oafl the carrier Ztl integral with a. hub; 29a, and, are-roe tatable asa unit. with, a. planet gear' 25 secured to` the shaft. 23; on the; other side of' the planet carrier. Each planet, gear.I 25. meshes witha second planet pinion 2B rotatable on a stud 2:1; fixed? to the .carrier 24, which is integral with or: securedl tnJ another planet gear 28- meshingI with ank intermediate sun gear- 29 rotatably mounted on the drivel shaft extension L9;

The intermediate ,sun gear 29: meshes wit-h planetary idlers 3.6 rotatable on-studs; 3kV secured t0 a driven planetary carrier; 32, which may. be driven .atx-various relative speeds. 'Each idler 39 meshes with a planet pinion ,33, fixed; on .one side of the, .carrier 3:22 to a sha-ft, 3,4;l rotatably mounted therein. yThe shaft-3.42 projects fromthe other; side .ot the `carrier- 4where. a. .driven planet gear is secured to it, meshing with a .driving sun; gear 36 rotatably mounted on the drive. extension lig. This sun` gear is integr-al, or other? Wise secured to rotate, with a primary driven gear: '31, whichV is rotated bythe ydrive gear i8 through asuitable variablespeed transmission 33:

'fllheqvariable speed tra-,nsmission is driven irorn the drivzegear l;8 secured :to the drive-shaft; The drive gear llll meshes with an idler 39 rotatably mounted .on astud' 49 i'ixedwtov the bottom casing wall,` 12;' which veng-ages .a gearl lll rotatably mounted onr another studV 42' xed to this wall, to which is secured a` bevel pinion .431' meshing with a, conflpanion4 bevel gear litY attached to the driving shaft 45' of the variable speed transmissioni; This shaft isV rotatably mounted inthe casing web e113 and 'in the endA wall I5 or the casing.

The drive shaft 45 has keyed kor otherwise suitably xed thereto. a plurality ofv stepped gears 46' reducing progressively in size- -from the largest gear atlone end to `.the smallest gear at the other end; in effect forming a cone gear Positioned at one sidefof this cone geanand disposed in yparalleli relation to ithe peripheries of yits several gears, is a primary jack shaft 412 journaled in the casing web i3: and having a :bevel :pinion 43 tiredv to its inner end mesltf ing with a companion bevel gear 49 rotatably mounted on a stud 50 secured to the bottom casing wall I2 and fixed to a gear 5I meshing with an idler 52 revoluble on a stud 53 iixed to the casing Wall I2, which, in turn, meshes with the primary driven gear 31, which is integral with the driving sun gear 35.

A secondary jack shaft 54 is journaled in the casing `web I3, being disposed on the opposite side of the gear cone 45 in a manner similar to the disposition of the primary shaft 41. A worm 55 is secured to this shaft and meshes with a worm wheel 56, which is the peripheral portion of the driven planetary carrier 32.

An axially adjustable primary gear 51 is secured in driving relation on the primary shaft 41, and is shiftable thereon to mesh with any one of the cone gears 46. To this end, the primary gear is secured on the inner end of an elongated sleeve 58 which extends through an opening 59 in the end Wall I5 of the casing and is axially slideable on the shaft 41. rIhe primary gear 51 may be secured on the sleeve 59 by any suitable means, such as a slide snap ring 59 partly submerged in a circular groove formed in said sleeve, and said sleeve and gear are splined to rotate with the shaft.

A secondary gear 65 is mounted in a similar manner on an elongated sleeve 66 slideably splined on the secondary jack shaft 54. Both sleeves 58, S6 are provided with a plurality of relatively spaced circular grooves 61 corresponding in number and relative spacing with the several cone gears comprising the composite gear cone 46.

Mounted on the casing wall l5 is a retaining plate 59 adjustably clamped to the wall I5 by means of clamp screws 19. -The plate 59 engages the grooves 61 in the sleeves 58 and 69 and thus, when clamp screws 19 are tightened, clamps the sleeve in selected position. By loosening the screws and disengaging the plate 59 from the grooves 61, either or both sleeves can be moved axially to another selected position to bring the desired cone gears into mesh.

It is apparent from the preceding description of the transmission mechanism that the driving ratio between the drive shaft i6 and the primary driving sun gear 35 may be varied by shifting the primary gear 51 into selective engagement with the desired gear of the composite cone gear 46. Similarly, the transmission ratio between the drive shaft I6 and the worm wheel planet carrier 32 may be varied by shifting the secondary gear 65 into engagement with a selected cone gear 45. By virtue of the different combinations of ratios of transmission with respect to the drive shaft that the worm wheel carrier 32 and the driving sun gear 35 can be operated, a large number of transmission ratios between the drive shaft I6 and the ultimately driven shaft 20 can be correspondingly obtained. In the specific arrangement disclosed, the number of different transmission ratios possible is a square of the number of gears comprising the composite cone gear 46.

The variable drive between the driving pinion I8 and the driving sun gear 36 is such as to provide a relatively coarse increment of adjustment in the rotation of the driven shaft 29 with respect to the driving shaft I5. On the other hand, the variable drive between this pinion I8 and the worm wheel carrier 32 is such as to provide a relatively ne increment of adjustment in the rotation of the drivenshaft relative to the drive shaft. Such ne adjustment is obtained, in the instant case, through suitable choice of the transmission ratio between the pinion I8 and Worm 55. Since the rotation of the driven shaft 29 is dependent upon the fixed speed of planet carrier 24 and upon the relative speeds and directions of rotation of the primary sun pinion 3G and the variably driven carrier 32, many diiierent ratios of transmission can be obtained by the mechanism herein described.

It is to be noted that there are, in effect, two planetary transmissions contained within the gear case, whose motions are combined to provide the ultimate result on the driven shaft. The rst, or primary, transmission provides a variable speed drive on the intermediate sun gear 29, depending upon the speeds and rotational directions of the driving sun gear 36 and worm wheel carrier 32. The second, or secondary, planetary transmission compounds the motion of the intermediate sun gear 29 and the secondary planetary carrier 24, which is secured to the drive shaft extension I9, to produce a resultant drive on the ultimate driven sun gear 2| secured to the driven shaft 20.

Ii it is assumed that the drive shaft I6 is rotating in a clockwise direction, the primary driving sun gear 36 will be driven through the gear train I8, 39, 4I, 43, 44, 46, 51, 48, 49, 5I, 52 and 31 including the variable speed sliding gear transmission 38 in a counterclockwise direction. Assuming that the worm wheel carrier 32 is stationary the primary planet gear train 35, 35, 33, 39, 29 is such that counterclockwise rotation of the primary driving sun gear 36 eects clockwise rotation of the intermediate sun gear 29 rotatably mounted on the drive shaft extension I9. The drive from the driving gear I8 through the cone gear transmission 38 to the worm wheel carrier 32 is such that the latter is rotated in a clockwise direction. If the driving sun gear 36 were stationary, each revolution of the carrier 32 would impart more than one revolution to the intermediate sun gear 29 in a clockwise direction, depending upon the gear ratio in the primary planetary train 36, 35, 33, 30, 29. Since the driving sun gear 36 and planet carrier 32 are both tending to drive the intermediate sun gear 29 in a clockwise direction, their motions add to one another to produce a resultant, greater rotation of the sun gear 29 than each of the former imparts to it alone.

Assuming that the secondary planet carrier 24 is stationary, the arrangement of the planet gears 28, 26, 25, 22 carried thereon and the drive from the intermediate sun gear 29 to the driven sun gear 2| is such as to tend to drive the latter in a counterclockwise direction. The secondary planet carrier, being xed to the drive shaft extension I9, rotates in a clockwise direction and tends to carry the driven sun gear .2l around with it in a clockwise direction. Assuming the intermediate sun gear 29 to be stationary, each revolution of the secondary carrier 24 tends to rotate the driven sun gear more than one revolution, depending upon the gear ratio in the secondary planetary train 29, 28, 26, 25, 22, 2I. Since the rotating intermediate sun gear 29 is tending to drive the driven sun gear 2| in a counterclockwise direction, the net result is for the rotating intermediate sun gear 29 to subtract from the clockwise rotation imparted to the driven shaft 20 by the clockwise rotating secondary carrier 24,

5 which carries the secondary planet gearsr 28, 2S, 2&5 22 around with it ina clockwisedirection.

WThile the ratios of transmission between the Various gea-rs can be suitably. chosen in accordance with` the use to which the transmission is to` be put, the various` gear trains that `have been employed are such as to permit a large number ofi relatively minute fractional increments oi adjustment to be made in the transmission ratio between the drive and driven shafts. For eX- ample, the eleven cone gears 4t shown in the drawings permit one hundred and twenty-one variations of the transmission ratio to be eiected. The sinaliness of the increments of adjustment andthe mode of operation of the planetary transmission lcan perhaps be better explained by reierence to an. actual transmissiony design.

Inthe illustrated embodiment oi the invention, thetransmission ratio 'between the primary drive shaftv it and cone gear shaft i5 is one to one by suitably choosing the numbers of teeth on the driving pinion i3, idler it, driven gear bevel pinion i3 and bevel gear 44. Similarly, the ratio of transmission between the primary jack. shaft il and driving sun gear tt is one to one, through gg;

suitable choice in the numbers of teeth on the bevel., gears et, fis, pinion 5i, idler gear and drivengear 3?. These two gear trains are interu connected through the coarse adjustment jack shaft gear 5l and the selected cone gear with i whichl it` meshes. In View of the iact that the transmission ratios between the driving pinion It and cone gear drive shaft lii', and between the primary jack shaft lil' and primary sun gear 36, are-'both one to one, the transmission ratio between the drive shaft it and driving sun gear will be the same as the transmission ratio ben tween the selected cone gear it and its i., eshing primary jack shaft gear 5l. The largest gear of the cone gear stack has 22 teeth and the smallest gear l2 teeth, each successive gear from the largest to the smallest progressively having one less tooth on its periphery. The primary jack shaft gear Si? has 20 teeth, providing eleven pospinion 2.5. integraltherewith twelve teethgand: if it be further assumed; that; the. planet: gear 2 5 meshing with the latter pinion has twenty-four teeth and rotatesy a sixteen-tooth planet gear 22 secured to its shaft. 23; which meshes with the driven sun gear 2l having thirty-two teeth, and further assuming that the planet gear carrier 2t is stationary, it is. evident that each revolution of the intermediate sun gear 29.in aclockwise direction effects one-eighth of a revolution of the driven sun gear 2l in a counterclockwise direction.

If the driving. sunv gear 3S were stationary, the one to one ratio of the primari7 planet gear train 36, 35, 33, 363, 29 would cause one revolution of the worm wheel carrier 32 in a clockwise direction to produce two revolutions of the intermediate sun gear 29 inl a clockwise direction. In other words, the rotation of the worm wheel planet carrier 32 produces double the amount of its rotation on the intermediate driven sun gear 29. Correspondingly, assuming` the intermediate driven sun gear 29 to be stationary, each revolution of the secondary planet carrier 2t in a clockwise direction would produce one and one-eighth revolutions of the driven sun gear 2l in a clockwise direction, because ofY the eight to one ratio of transmission in the planet gear train from the intermediate sun gear 29 to the driven sun gear 2|, or a total of. 1.125 revolutions of the driven sun gear.

Since the secondary planet carrier 2d isinxed to rotate with the primary drive shaft lli-each revolution of such carrier with the intermediate "i sun gear 2Q stationary would rotate the: driven sun gear 1.125 revolutions. However, since the intermediate sun gear 29` is not stationary, it has the effect, as afore-mentioned, of` rotating the driven sun gear 2l and driven shaft 2i): in a counterclockwise direction, decreasing the speed sible transmission ratios between the drive shaft '-E iii, and driving sun gear 3@ of from 22/26 to 12/20; or 1.1 to 0.6.

The transmission ratio between the worm 55 and the worm wheel 55 is chosen, in the particu lar example being described, as 22 to l. In View of the one to one ratio between the drive shaft i5 and the cone gear drive shaft -i'a, the trans-y mission ratio between the driving shaft iii and the worm wheel planet carrier 32 will be twentytwo times the ratio between the cone gear drive shaft 45 and the secondary driven gear In the primary planetary train, the driving sungear Sii may be assumed to have twenty teeth, thev planet gear meshing therewith twenty teeth, the planet pinion 33 iixed to rotate with this planet gear sixteen teeth, and the intermediate driven sun gear 2 has sixteen teeth, (The number ci" teeth on the planet idler 3@ is immaterial.) The ratio of transmission between the primary driving sun pinion 3S and the intermediate driven sun gear 29 is, therefore, one to one, with the intermediate sun gear 2Q rotating in the opposite direction to that of the primary driving sun pinion 3S. Since the latter is being rotated in a counterclockwise direction upon clockwise movement oi the primary drive shaft, thefsun gear 2e will be rotated in a clockwise din rection.

If it -is` assumed that the planet gear 23 on the secondary carrier, 24 has thirty-two teeth and .the

of the latter by one-eighth of the speed of the intermediate sun gear. In other words, the rotation of the driven shaft 2U for each revolution of the drive shaft lli may be expressed as follows:

(l) SU=1.125-1;S1

in which Suzthe rotation of the driven shaft 2t; and S1=the rotation of the intermediate sun gear Z9 The rotation imparted to the intermediate sun gear 29 for each revolution of. the drive shaft It is equal to twice the rotation of the worm wheel carrier 32 plus the rotation of the driving sun gear 3B, or

in which W=the rotation of worm wheel carrier' 32, and SD=the rotation of the driving sun gear 36 Substituting for Si in Equation 1, as mined from Equation 2,

deterthe carrier 32 with respect to the driving shaft I6 may be expressed as follows:

P W: 1/22 XE in which P=number of teeth on selected cone gear 4S, and R=20=number of teeth on secondary jack shaft gear 65 The rotation SD of the sun gear 36 relative to the drive shaft I6 may be expressed in the following manner:

F SD= in which F= number of teeth on selected cone gear 16, and

G==number of teeth on primary jack shaft gear 51 Substituting the foregoing in Equation 3 above;

(6) SU=1.125-0.0005681818(P4-11F) From the foregoing Equation 6 it can readily be demonstrated that very fine increments of adjustment in the transmission ratio are possible. Assuming that the primary jack shaft gear 5i is meshing with the largest cone gear 46 having twenty-two teeth, factor F, and that the secondary jack shaft gear 65 is also meshing With this twenty-two-tooth cone gear 46, factor P, the number of revolutions which the driven shaft 20 makes for each revolution of the driving shaft i 6 may be computed by substituting in the above Formula 6, an-d will be found to be 0.975.

Again, assuming that the coarse adjustment obtained by driving through the cone transmission 38 onto the primary driving sun gear 36 remains unchanged, that is, that the primary jack shaft gear 57 meshes with the twenty-twotooth gear, factor F, but that the fine adjustment secondary gear 65 has now been meshed with the next gear having twenty-one teeth, factor P, substitution in the above formula shows that the driven shaft 20 is rotated 097556818 revolutions for each revolution of the driving shaft. In other words, the rotation of the driven shaft with respect to the driin'ng shaft has increased by 0.00056818. If the primary jack shaft gear 51 remains meshing with the twenty-twotooth gear, factor F, and the secondary jack shaft gear 65 is meshed with the twenty-toothed gear, factor P, it will be found that the rotation of the driven shaft 20 for each revolution of the driving shaft I6 will be increased still further by 0.00056818 or to 0.976136.

Further changes in transmission ratio can be made by shifting the fine adjustment gear 05 along the cone 46. For each fixed position of the coarse adjustment jack shaft gear 51' there are eleven positions ofthe fine adjustment gear 65, and since the coarse adjustment gear has eleven positions, the net result is Vto provide one hundred twenty-one possible transmission ratios, which, as demonstrated above, can vary by as little as 0.00056818 for the specifically designed transmission referred to.

In the specific example given, the transmission operates with a ratio in the neighborhood of one to one for each selected position of the pinion and secondary jack shaft gears. For instance, 0.975, 0.97556818, etc. This furnishes an efficient power transmission arrangement, since the entire device can operate with a lesser overall torque than heretofore inherent in transmissions of the type under consideration.

It is, accordingly, apparent that a planetary transmission has been devised in which a large number of very small increments of adjustment can be made in the transmission ratio between the driving land driven members. The gear drive is at all times positive in character, providing a simple and effective way of compensating for errors that would otherwise be introduced in meter readings due to temperature and pressure changes. Although particular reference has been made to the metering field, the transmission device has exceptional utility in other situations in which a positive transmission means capable of selective adjustment to produce exceedingly minute variations in transmission ratio is required.

Although a preferred form of the invention has been shown and described, and particular reference made to a specific design, it is to be understood that various changes may be made in the construction and relationship of the parts by those skilled in the art without departing from the spirit of the invention as defined in the appended claims.

Having thus described my invention, what I claim and desire to obtain by Letters Patent is:

l. In transmission mechanism of the nature disclosed, a drive member, a driven member, an intermediate sun gear rotatable relative to said members, a first planetary gear train connecting said members and including a driven sun gear fixed to said driven member, a planet carrier fixed to said drive member and planet gearing rotatably mounted on said carrier and meshing with said sun gears, a second planetary gear train including a driving sun gear and a second planet carrier rotatable relative to each other and to said members and a second planet gearing rotatably mounted on said second carrier and meshing with said intermediate sun gear and driving sun gear, and speed change means driven by said drive member for driving said driving sun gear and second carrier at variable relative speeds.

2. In transmission mechanism of the nature disclosed, -a drive shaft, a driven shaft, an intermediate sun gear rotatable relative to said shafts, a first planetary gear train connecting said shafts and including a driven sun gear fixed to said driven shaft, a planet carrier fixed to said drive shaft and planet gearing rotatably mounted on said carrier and meshincr with said sun gears, a second planetary gear train including a driving sun gear and a second planet carrier rotatable relative to each other and to said shafts and a second planet gearing rotatably mounted on said second carrier and meshing with said intermediate sun gear and driving sun gear, and variable speed change means between said driving sun gear and second carrier, said means being driven by said drive shaft.

3. In transmission mechanism of the nature disclosed, a drive shaft, a driven shaft, an intermediate sun gear rotatable relative to said shafts, a first planetary gear train connecting said shafts and including a driven sun gear fixed to said driven shaft, a planet carrier fixed to said drive shaft and planet gearing rotatably ymounted on said carrier and meshing With said sun gears, a second planetary gear train including a driving sun gear and a second planet carrier rotatable relative to each other and to said shafts and second planet gearing rotatably mounted on said second Jcarrier and meshing vwith said intermediate sun gear and driving sun gear, and speed change means driven by said driveshaft for driving said driving sun gear and second carrier in opposite directions at variable speeds.

4. In transmission mechanism of the nature disclosed, drive and driven shafts, an intermediate sun gear rotatable relative to said shafts, a first planetary gear train connecting said shafts and including a driven sun gear fixed to said driven shaft, a planet carrier fixed to said drive shaft and planet gearing rotatably mounted on said carrier and meshing with said sun gears, a second planetary gear train including a driving sun gear and a second planet carrier rotatable relative to each other and to said shafts and second planet gearing rotatably mounted on said second carrier and meshing with said intermediate sun gear and driving sun gear, said shafts, sun gears and carriers being arranged coaxially, and speed change means driven by said drive shaft for driving said driving sun gear and second carrier at selected speeds.

5. In transmission mechanism of the nature disclosed, coaxial drive and driven shafts, an intern mediate sun gear rotatable on said drive shaft, a rst planetary gear train connecting 'said shafts and including a driven sun gear fixed to said driven shaft, a planet carrier fixed to said drive Shaft and planet gearing rotatably mounted on said carrier and meshing with said sun gears, a second planetary gear train including a driving sun gear and a second planet carrier both rotatable on said drive shaft relative to each other and second planetl gearing rotatably mounted on said second carrier and meshing with said intermediate sun gear and driving sun gear, and speed change means driven by said drive shaft for driving said driving sun gear and second carrier at selected speeds.

6. In transmission mechanism of the nature disclosed, drive and driven shafts, an intermediate sun gear rotatable relative to said shafts, a first planetary gear train connecting said shafts and including a driven sun gear fixed to said driven shaft, a planet carrier fixed to said drive shaft and planet gearing rotatably mounted on said carrier and meshing with said sun gears, said planet gearing being such that said intermediate sun gear tends to rotate said driven sun gear in a direction opposite to that of said intermediate sun gear, a second planetary gear train including a driving sun gear and a second planet carrier rotatable relative to each other and to said shafts and second planet gearing rotatably mounted on said second carrier and meshing with said intermediate sun gear and driving sun gear, said second planet gearing being such that said driving sun gear tends to rotate said intermediate sun gear in a direction opposite to that of said driving sun gear, and speed change means driven by said drive shaft for driving said driving sun gear and second carrier in opposite directions at selected speeds.

'7. In transmission mechanism of the nature disclosed, drive and driven shafts, an interme diate sun gear rotatable relative to said shafts, a first planetary gear train connecting said shafts and including a driven sun gear fixed to said driven shaft, a planet carrier` fixed to said vdrive shaft and planet gearing rotatably mounted on said carrier and meshing with said sun gears, said planet gearing being such that said intermediate sun gear tends to rotate said driven sun gear in a direction opposite to that of said intermediate sun gear, a second planetary gear train including a driving sun gear and a second planet carrier rotatable relative to each other and `rto said shafts and second planet gearing rotatably mounted on said second carrier and meshing with said intermediate sun gear and driving sun gear, said second planet gearing being such that said driving sun gear tends to rotate said intermediate sun gear in a direction 'opposite to that of said driving sun gear, said shafts, sun gears, and carriers being arranged coaXially, and 'speed change means driven `by said drive shaft for driving said driving sun gear and second carrier in opposite directions at selected speeds.

8. In transmission mechanism of the nature disclosed, coaxial drive and driven shafts, an intermediate sun gear rotatable on said drive shaft, a rst planetary gear train connecting said shafts and including a driven sun gear fixed to said driven shaft, a planet carrier Xed to said drive shaft and planet gearing rotatably mounted on said carrier and meshing With said sun gears, said planet gearing being such that said intermediate sun gear tends to rotate said driven sun gear in a direction opposite to that of said intermediate sun gear, a second planetary gear train including a driving sun gear and a second planet carrier both rotatable on said drive shaft relative to each other and second planet gearing rotatably mounted on said second carrier and meshing with said intermediate sun gear and driving sun gear, said second planet gearing being such that said driving sun gear tends to rotate said intermediate sun gear in a direction opposite to that of said driving sun gear, and speed change means driven by said drive shaft for driving said driving sun gear and second carrier in opposite directions at selected speeds.

9. In a transmission mechanism of the nature disclosed, coaxial drive and driven shafts, an intermediate sun gear rotatable on said drive shaft, a first planetary gear train connecting said shafts and including a sun gear fixed to said driven shaft, a planet carrier fixed to said drive shaft and planet gearing rotatably mounted on said carrier and meshing with said sun gears, said planet gearing being such that said intermediate sun gear tends to rotate the driven sun gear in a direction opposite to that of and at a slower speed than said intermediate sun gear, a second planetary gear train including a driving sun gear and a second planet carrier both rotatable on said drive shaft relative to each other and second planet gearing rotatably mounted on said second carrier and meshing with said first sun gear and driving sun gear.4 said second planet gearing being such that said driving sun gear tends to rotate said intermediate sun gear in a direction opposite to that of said driving sun gear, and speed change means driven by said drive shaft for driving said driving sun gear and second carrier in opposite directions at selected speeds.

10. A transmission mechanism of the nature disclosed, coaxial drive and driven shafts, an intermediate sun gear rotatable on said drive shaft, a driven sun gear xed to the driven shaft, a planet carrier fixed to said drive shaft, a first planet gear rotatable on said carrier and meshing with said driven sun gear, a second planet 1 l. 12 gearxed to rotate with said rst planet gear, REFERENCES CITED a third planet gear rotatable on said carrier and meshing with Said second planet gear, a fourth The following references are of record in the planet gear xed to rotate with said third planet le 0f this patenti gear and meshing with said intermediate sun UNITED STATES PATENTS gear, a driving sun gear and a second planet carrier both rotatable on said drive shaft relative Number Name Date termediate sun gear and with said sixth planet gear, and speed change means driven by said Number comfltry Date n drive shaft for driving said driving sun gear and i5 101,515 Austraha July 15 1907 second carrier in opposite directions at selected speeds.

WILLIAM F. BERCK. 

